How to send a notification that's handled by ON_NOTIFY?

Question

I\'m trying to post a LVN_ ITEMCHANGED to my custom gridlist\'s owner. I know how to send a WM_ User message using PostMessage (as shown here)

::PostMessage         


        

Answer 1

Send WM_NOTIFY, pass control id as wParam and NMHDR* as lParam.

You'll need to allocate an NMHDR variable and fill it appropriately - set code to LVN_ITEMCHANGED and idFrom to the control id. You can only use SendMessage(), not PostMessage() since the receiving party will directly read memory through the NMHDR* pointer.

Smth like this:

NMHDR nmhdr;
nmhdr.code = LVN_ITEMCHANGED;
nmhdr.idFrom = controlId;
nmhdr.hwndFrom = controlWindowHandle;
SendMessage( targetWindowHandle, WM_NOTIFY, controlId, &nmhdr );

Answer 2

I found out that I could override the message handler in my derived class and pass the message on to my parent control simply by using this code in the message map:

ON_NOTIFY_REFLECT_EX(LVN_ITEMCHANGED, OnListItemChanged)

Then in OnListItemChanged, I first call the base class function then return FALSE. This causes the message to be reflected to the parent class effortlessly.